The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1887-02-27
ORIGIN OF INDIANA FLORA.
Evidences Of the State Having Been the
Theater of Two Glacial Inyasions.
Important Scientific Information Contained
In Paper Disclosing the investigations
of a Distinguished Indiana Botanist.

port JUST lsSaeA from tue INDIANA department. VI
Geology and Natural History is that pertaining
to the origin of the wild plants of the State
There are no subjects in biology OF greater IN
terest than the distribution of plants and ami
mails, and how they came to occupy the locail-
ties where they are now found by the zoolosist
and botanist. Previous to the appearance OF
Charles Darwins 'iOrigin of Species and of
Alfred Wallaces 'sIsand Life" in 1858, it was
generally thought that plants were restricted to
the places where they were found growing, and
that they must endure or succumb to
any changes Of climate unfavorabie to
them. Animals were regarded as mi
gratory, and plants as fixed, and, in the
minds of the scientists of half century
ago these migrations took the form of actual and
long marches of individuals after water or bet
ter food, or before stronger animals. Such mi
grations were caused by sudden and radical
changes of climate, and the animals marched off
In body, and left the plants helpless. But Ly
ell showed that cataclysms or sudden catastro-
Plies have rarely occurred in the crust of the
earth, and that the causes now in operation
air, water, organic life and gradual shrinkage of
the earth's crust-are sufficient to account for
the primary formation and subsequent changes
Of the earth's land masses. For instance, while
the great mountain masses Of the Appalachian
system, now thousand miles in length and two
hundred wide, once lay at the bottom of the sea,
az fat masses of sedimentary rock,
and are now elevated and crumpled
into successive mountain pillows and
occupy perhaps less than half their original area,
these changes have taken place so gradually
that successive nations might have risen,
tired and passed into decay. with no knowledge
OF the momentous changes going about them.
Such conceptions of continental change and
consequent climatic variations ms Lyell demon
strated. modified at the whole teaching
rs to plant and animal migration. as Darwin and
VOLTAGE, following Lyell, have shown, and their
views are growing more and more into promi-
pehce. In their extended treatise the origin
of the Indiana hora published in the present
report, Profs. Coulter and Thompson, his assist
ant, of Wabash College, have elaborated and
specialized, and applied to the 800 native
plants of Indiana the modern teaching that the
present plants and animals of country are not
indigenous but are emigrants driven before un-
favorable physical changes or permitted to en-
ter by the removal of barriers. Just as Europe
has been the meeting place Of streams of human
migration from several points Of the compass
which thus met and contended with each other
for mastery, so the plants or animals Of any re.
gion must be considered as the resultant of such
a conflict between invaders from every direction
and the native species"
The object of Professor Couter's paper the
result of ten years careful study CT the Indiana
hora-s to discover what plants of the State
are to be considered invaders from what direc-
tions and regions they have come, what were
the native forms displaced, and to what extent
the invaders have been driven back or have sue
eeedec In maintaining a fcothold. But these
studies have deeper value than merely bo-
tanical or biological one. They are proofs for
Or against the prevalent geological changes tell
ing OF climate and Lard changes 10 the past cor
roooratlDg the great geological concepts and
placing historical geology upon a surer basis.
just the entombed remains of plants in the
Indiana rocks carry the history of plants back
into the remote past, and are silent witnesses OF
their former movements and distribution, so the
study of the present living forms and their re-
lationship to the kinds north and south of the
State tell of more recent geological and climatic
changes
The great dominating feature of Indiana
geology is the glacial age. Throughout the
northern and central parts of Indiana the soil
has been formed and modified by the drift de
posts which overiie the sea formed rock from
ten to two hundred feet In depth. and which
was brought from widely separated directions
and localities by the glacial ice sheet during the
great ice age. This transported material is cut
by river systems conforming to the great water
sheds determined mainly by the elevation and
slope of the underlying country rock. These
streams permeating every square mile OF the
State, drain the storm waters off through the
st. Joseph into Lake Michigan, through the
Maumee into Lake kre, the Kankakee 10 the
Mississippi and the Wabash to the Ohio Five
eixths of the State is drained through the
Wabash and kankakee into the Mississippi while
the nortneaste tern counties enter the lake drain
age and go to the sea by the St. Lawrence. The
impress of these two great drainage systeme
upon plants and their dis tribution is marked
as the greatest couriers Of seeds within coun
try are its streams, and the range OF Plants in
any country can DO measured by the extent oil
fhn droI IF Of Orxt1. ~
It,
The southern counties have the widest range
OF plants, as they are brought down by the extern
sive drainage of the Ohio from the lake region
OF the north and the Allegheny mountain region
OF the east. while other plants have wandered
up the river from the Gulf States the south.
The interior streams in the same way have
served to distribute our own plants more uni
formly over the State The streams taken il
connection with the winds which blow ali gh
and winged seeds wide abroad. and the bird
which carry heavy seeds in the mud on thei
feet, and indiGestible in their disestiy,
tract, have aided in the disss mnation of plant:
in ali directions. But these are permitted" Of
accidental causes of plant migration, and t.
them is to be added a series of Compulsory
causes, the leading one of which is change o.
climate
The most stupendous change of climate which
geology reveals is that brought about by thu
great lee age. when the polar ice-cap extended
down into what now temperate ATTITUDES
This great ice mass, thousand feet thick OIL
more, extended slowly across Indiana. its lower
limit being the southern borders Thi.
sphercal extension of arctic conditions drove
the plants of northern Europe, Asia and Amer
lea, along with the animals which suhslstet
upon them, into the southern parts of these con
tjnents After a lapse of centuries warmer con
dtions prevailed, melting the ice masses which
would retreat ana permit or compel piant
to move north again. These alternate move
ments may have been repeated several times
and are no doubt, the most important explana
ton of the origin and composite nature OF In
diana fora.
Over three hundred eastern North America
plants are also indigenous TO Europe, while over
thousand of the four thousand east of the Mis-
ole